Maize: Extraction

Why planting a week too late can ruin a crop

Maize is a warm-season grass first cultivated in Central America around 5000 BC (Geman, pdf p. 160). In the US Corn Belt it is sown in spring; planted too late, it pollinates in peak summer heat and risks early frost. Pollination in July is the make-or-break moment, so a heatwave can move prices (Morgan, pdf p. 305). Almost all US corn, and most in Argentina and Brazil, grows from hybrid seed sold by a handful of firms (Morgan, pdf p. 331). Brazil adds a second crop after soybeans. Mills turn the grain into feed, starch, sweeteners and ethanol, with distillers' grains returned to feed.

Maize gives more grain per hectare than any other cereal, but yields range from over 11 t/ha in the US to under 4 t/ha in India and much of Africa. The gap reflects hybrid seed, nitrogen, irrigation and mechanisation. Three systems supply the market. The US Corn Belt runs high-input, rainfed, fully mechanised farms. Brazil grows most of its maize as a second crop sown straight after soybeans. China, India and Africa grow maize mainly on small farms for feed and food. After harvest, grain is fed whole, distilled for ethanol or wet-milled into starch and sweeteners.

Methods compared

How each method works

Genetically modified hybrids are planted at high density with heavy nitrogen, usually rotated with soybeans. Large planters and combines handle hundreds of hectares per worker. Most US maize is rainfed, so July weather decides the crop.

Highest yields and cheapest export maize; exposed to US summer drought and nitrogen prices.

Farmers in Mato Grosso and Paraná sow maize straight after harvesting soybeans in January-March, using the same land twice a year. Yields depend on when the rains end. The crop is exported from July onwards, alternating with US supplies.

Low land cost and fast growth; vulnerable to an early end of the rainy season.

Small farms grow maize for feed mills, starch plants and home food. China's north-east has larger mechanised farms; India grows a rainfed kharif crop and an irrigated rabi crop in Bihar and the south. Inputs and hybrid use vary widely.

Large room to raise yields; low mechanisation and weather risk.

Dry-grind plants mill whole maize, ferment the starch to ethanol and sell the remaining protein, fibre and oil as distillers grains and corn oil. Wet mills soak the grain and separate starch, gluten, fibre and germ, then convert starch to sweeteners, ethanol or industrial starch.

Adds value and feed co-products; margins swing with petrol and maize prices.

Who does it: global

Who does it: India

India grew about 40 Mt of maize in 2024 (3.3% of world output, 3.54 t/ha; FAOSTAT). Poultry feed was the main use, but maize became India's largest ethanol feedstock in 2024-25, supplying about half of 10.39 billion litres (AIDA), which has tightened domestic supply.